CARC 21: This injury/illness is the liability of the no-fault carrier
Your insurer says a no-fault auto policy (PIP coverage) should pay for this care first.
What this means for your claim
In no-fault states, Personal Injury Protection (PIP) coverage on an auto policy is the primary payer for accident-related medical care, regardless of who caused the accident. Your health plan can deny until PIP benefits are exhausted.
What to do next
- 1
If the care relates to a car accident, submit the claim to your auto insurer's PIP coverage first.
- 2
Once PIP benefits are exhausted, provide your health insurer with documentation so they can process the remaining balance.
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If the injury was unrelated to a vehicle, dispute the classification in writing with your health insurer.
How to handle a non-covered or denied service
Non-covered codes mean the insurer is declining to pay — either because the plan excludes the service, because medical necessity wasn't established, or because a requirement like prior authorization or timely filing wasn't met. These are the adjustments most worth contesting, because a denial is not the final word: a large share of denials are overturned on appeal when the patient or provider supplies the right documentation.
Find the exact reason for the denial in writing
"Not covered" is a category, not an explanation. Call your insurer and ask specifically why: Is the service excluded from your plan? Was it deemed not medically necessary? Was prior authorization missing? Was the claim filed late by the provider? The precise reason determines who fixes it and how.
Decide whether it's the provider's error or a true plan exclusion
If the problem is a missing prior authorization, a coding error, or late filing, that is usually the provider's responsibility — and in many states they cannot bill you for their own administrative mistakes. If the service is genuinely excluded from your plan, your path is an appeal or financial assistance, not a billing correction.
Gather support for medical necessity before you appeal
When a denial is based on medical necessity, ask your treating physician for a letter of medical necessity and the clinical notes that justify the service. Insurers overturn a meaningful portion of these denials once the supporting documentation is in front of a reviewer.
Your appeal rights for CARC 21
You have a federally protected right to appeal a denial. Request the insurer's full reason and your plan's appeal deadline in writing, then file an internal appeal with your supporting documents. If the internal appeal is denied, you can request an independent external review — a reviewer with no financial stake in the outcome. If the service was an emergency or from an out-of-network provider at an in-network facility, the federal No Surprises Act may also protect you from balance billing.
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